8237372: NullPointerException in TabPaneSkin.stopDrag

Reviewed-by: arapte

Author: Robert Lichtenberger

modules/javafx.controls/src/main/java/javafx/scene/control/skin/TabPaneSkin.java

@@ -2210,17 +2210,17 @@ private void stopDrag() {
         if (dragState == DragState.START) {
             // No drag action was performed.
             resetDrag();
-            return;
-        }
-        // Animate tab header being dragged to its final position.
-        dragHeaderSourceX = dragTabHeader.getLayoutX();
-        dragHeaderTransitionX = dragHeaderDestX - dragHeaderSourceX;
-        dragHeaderAnim.playFromStart();
-
-        // Reorder the tab list.
-        if (dragHeaderStartX != dragHeaderDestX) {
-            ((TabObservableList<Tab>) getSkinnable().getTabs()).reorder(dragTabHeader.tab, swapTab);
-            swapTab = null;
+        } else if (dragState == DragState.REORDER) {
+            // Animate tab header being dragged to its final position.
+            dragHeaderSourceX = dragTabHeader.getLayoutX();
+            dragHeaderTransitionX = dragHeaderDestX - dragHeaderSourceX;
+            dragHeaderAnim.playFromStart();
+
+            // Reorder the tab list.
+            if (dragHeaderStartX != dragHeaderDestX) {
+                ((TabObservableList<Tab>) getSkinnable().getTabs()).reorder(dragTabHeader.tab, swapTab);
+                swapTab = null;
+            }
         }
     }
 

modules/javafx.controls/src/test/java/test/javafx/scene/control/TabPaneTest.java

@@ -463,6 +463,23 @@ private void show() {
         assertSame(TabPane.TabDragPolicy.FIXED, tabPane.getTabDragPolicy());
     }
 
+    @Test public void tabDragPolicyReorderAndAsymmetricMouseEvent() {
+        tabPane.setTabDragPolicy(TabPane.TabDragPolicy.REORDER);
+        tabPane.getTabs().add(tab1);
+        tabPane.getTabs().add(tab2);
+        root.getChildren().add(tabPane);
+        show();
+
+        root.layout();
+
+        double xval = (tabPane.localToScene(tabPane.getLayoutBounds())).getMinX();
+        double yval = (tabPane.localToScene(tabPane.getLayoutBounds())).getMinY();
+
+        SceneHelper.processMouseEvent(scene,
+            MouseEventGenerator.generateMouseEvent(MouseEvent.MOUSE_RELEASED, xval+75, yval+20));
+        tk.firePulse();
+    }
+
     @Test public void setRotateGraphicAndSeeValueIsReflectedInModel() {
         tabPane.setRotateGraphic(true);
         assertTrue(tabPane.rotateGraphicProperty().getValue());